I have development tools up and running on MBL 2tb on latest fw. (unfortunately I'm no programmer)
Its quite capable machine i have to say
I'm looking way to unlock and use hardware crypto accelerator & run own kernel and even upgrade to debian 7.0
There is thread on community.wdc.com where we can find that enabling hardware crypto will close doors to some markets.

I have sources from WD and netgear WNDR4700 (is based on the same chipset) and they share same kernel version 2.6.32-11
There are people that try port openwrt on WNDR4700 and we can also benefit from it.
AMCC submitted opensource kernel drivers to crypto4xx so all should be in place.

I've bought a second MBL for $25 without disk to install Debian Wheezy on it. I've decided to split this complex task into two pieces:

installing Debian Wheezy with stock kernel,

replace stock kernel with new one.

According a published here boot, taken from soldered serial console, we may take /boot and /lib/modules to the new root filesystem. Other rootfs files may be filled with deboostrap package by this guide.

(oops, no links for newbies, guide named "D.3. Installing Debian GNU/Linux from a Unix/Linux System")

As for kernel, I was surprised that APM82181 SoC support was added to vanilla kernel tree ~1 year ago:

Looking into differences between vanilla 2.6.32-11 and GPL'ed 2.6.32-11, it was a great work done to support APM82181 SoC. And, unfortunately, it was not included to the next releases of vanilla kernel.
We can compile any kernel we want (even last one!), but without DMA, hw crypto and some other very usefull features. Look like APM82181 SoC was abandoned at ~2.6.32 release.
I've made a pull request to linux kernel git to make compilation with no errors. But, as I said, it's useless. I can't port SoC's features to new kernel alone, there is too much work.

Also, I've tried to replace user-space part with Debian Wheezy, but new udev uses "new" accept4() syscall that absent in 2.6.22-11. I can patch udev, but may be there is another packages uses accept4().

No dice on the image. I installed it with the debrick script and could not ssh into the drive as it was not found. Used a factory rootfs.img with the debrick script and the drive booted right up without issue

and developent hardware kit name if you like to search for kernel source or patches against EV-APM82181-KIT-01

It's called "bluestone" as a kernel target, a little fix needed to compile it — h-ttps://github.c-om/torvalds/linux/pull/33
Looks SoC support abandoned in those times. A modern kernel interfaces is quite different then used in 2.6.32.60, it's hard for me to port all necessary SoC drivers to new kenrel.